Most of the time we are not sure whether our applications are using discounted or depreciated version. Discounted versions anyway will fail, but depreciated features will work.
To identify depreciated features, now there is a new perfmon counter called, SQLServer:Depreciated Features.
This was my output, simply after adding these counters.
Above image shows SQL Server instance has 4 databases with compatibility level 90 and 2 databases with compatibility level 80. (Scale is x10). In SQL Server 2008, compatibility level 70 is discontinued while 80 and 90 compatibility levels are depreciated.
Following query has two depreciated features.
CREATE Table #
CREATE Table ##
DROP TABLE #
DROP TABLE ##
This will generate few more counters as you can see below.
This count is an aggregated counter and it will be reset to zero when the service is restated.